1. Field of the Invention
Aspects of the present invention relate to an auto document feeder and an image forming apparatus including the same, and more particularly, to an auto document feeder having a compatible driving module and an image forming apparatus including the same.
2. Description of the Related Art
In general, an auto document feeder is used as a kind of a document feeder, includes a scanning part to scan image data recorded on a document stacked in a document stacking stand, and is applied to apparatuses having an information inputting function, such as a scanner, a facsimile, a multi-functional device, and a photocopier. Auto document feeders are classified as a low speed auto document feeder or a high speed auto document feeder according to the document feeding speed. An auto document feeder includes a driving part to generate a driving force and a driving force generating unit having a driving force switching device to switch the driving force of the driving part in order to selectively feed documents. In conventional auto documents feeders, a one-way gear or a swing gear is used as the driving force switching device for the low speed auto document feeder, and an electronic clutch is used as the driving force switching device for the high speed auto document feeder.
As shown in FIG. 1, a conventional high speed auto document feeder 10 includes a driving motor 30 as a driving force generating device and an electronic clutch 20 as a driving force switching device. A driving force of the driving motor 30 is transmitted to an electronic clutch gear 20a via a driving pinion 41 and a transmission gear 42 engaged with the driving motor 30. The electronic clutch 20 transmits the driving force transmitted from the electronic clutch gear 20a to a rotating shaft 13 of an auto document feed roller 11 when power is turned on by a controller (not shown). The auto document feed roller 11 and a pickup roller 12, of which the mutual rotating shafts thereof are connected to each other by a pickup gear 32, rotate in the same direction 31a, thereby feeding the stacked document.
After the document is fed, the electronic clutch 20 is powered off and the rotating shaft 13 is kept idle. Then a bracket 50 accommodating the auto document feed roller 11 and the pick up roller 12 tends to rotate downward with respect to the rotating shaft 13 as a result of its own weight. A spring 60 connects a frame (not shown) with the bracket 50 and supports the bracket 50 by an elastic force to form a predetermined document stacking space.
However, a one-way gear used with the conventional low speed auto document feeder is not directly connected with the rotating shaft of the auto document feed roller, unlike the electronic clutch 20 which is directly connected to the rotating shaft of the conventional high speed auto document feeder. Instead, the one-way gear has a separate rotating shaft which engages a gear connected with the rotating shaft of the auto document feed roller.
In the high speed auto document feeder, since the electronic clutch 20 is directly connected with the rotating shaft 13 of the auto document feed roller 11, the low and the high speed auto document feeders have rotating shafts of the auto paper feed rollers with mutually different lengths. Also, since the electronic clutch 20 is directly connected with the rotating shaft of the auto paper feed roller, but the one-way gear has a separate rotating shaft, low and high speed auto document feeders are not mutually compatible.
Also, in the case of the high speed auto document feeder 10, it is not easy to detach the bracket 50, for example, after a paper jam, since the electronic clutch 20 is directly connected with the rotating shaft 13 by a power cable. Furthermore, since the elastic member 60 is connected with the bracket 50, it is exceedingly difficult to detach the bracket 50.